Shareholders' equity AOCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax			$ 50,519
Other comprehensive loss, before income tax	$ (1,772)	$ (3,559)	(1,305)	$ (12,113)
Other Comprehensive Income (Loss), Tax	0	(109)	104	(1,071)
Other Comprehensive Income (Loss), Net of Tax	(1,772)	(3,450)	(1,409)	(11,042)
Balance – end of period, net of tax	52,373	47,675	52,373	47,675
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	(6,809)	(5,713)	(7,279)	2,256
Balance – end of period, net of tax	(8,953)	(8,611)	(8,953)	(8,611)
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Including Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(2,240)	(3,324)	(1,935)	(12,898)
Net Realized Gains (Losses) Reclassified from AOCI	(70)	(279)	(357)	(857)
Other comprehensive loss, before income tax	(2,170)	(3,045)	(1,578)	(12,041)
Other Comprehensive Income (Loss), Tax	(29)	(147)	93	(1,174)
Other Comprehensive Income (Loss), Net of Tax	(2,141)	(2,898)	(1,671)	(10,867)
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	3	0	3	0
AOCI, Liability for Future Policy Benefit, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	(247)	(427)	(75)	(1,399)
Balance – end of period, net of tax	404	(5)	404	(5)
AOCI, Liability for Future Policy Benefit, Including Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive loss, before income tax	683	479	497	1,546
Other Comprehensive Income (Loss), Tax	35	57	21	152
Other Comprehensive Income (Loss), Net of Tax	648	422	476	1,394
AOCI, Liability for Future Policy Benefit, Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	(3)	0	(3)	0
AOCI, Market Risk Benefit, Instrument-Specific Credit Risk, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	(16)	(17)	(24)	(57)
Balance – end of period, net of tax	(21)	(9)	(21)	(9)
AOCI, Market Risk Benefit, Instrument-Specific Credit Risk, Including Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	(5)	8	3	48
AOCI, Market Risk Benefit, Instrument-Specific Credit Risk, Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	0	0	0	0
Cumulative Foreign Currency Translation Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	(2,920)	(2,768)	(2,966)	(2,114)
Balance – end of period, net of tax	(3,148)	(3,703)	(3,148)	(3,703)
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(314)	(942)	(269)	(1,631)
Net Realized Gains (Losses) Reclassified from AOCI	3	0	10	0
Other comprehensive loss, before income tax	(317)	(942)	(279)	(1,631)
Other Comprehensive Income (Loss), Tax	(13)	(7)	(21)	(42)
Other Comprehensive Income (Loss), Net of Tax	(304)	(935)	(258)	(1,589)
Accumulated Foreign Currency Adjustment Attributable to Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	(76)	0	(76)	0
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	(53)	0	(66)	0
Balance – end of period, net of tax	(22)	(49)	(22)	(49)
Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(17)	(94)	23	(94)
Net Realized Gains (Losses) Reclassified from AOCI	(55)	(32)	(32)	(32)
Other comprehensive loss, before income tax	38	(62)	55	(62)
Other Comprehensive Income (Loss), Tax	7	(13)	11	(13)
Other Comprehensive Income (Loss), Net of Tax	31	(49)	44	(49)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	0	0	0	0
Postretirement Benefit Liability Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	223	259	225	240
Balance – end of period, net of tax	222	261	222	261
Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive loss, before income tax	(1)	3	(3)	27
Other Comprehensive Income (Loss), Tax	0	1	0	6
Other Comprehensive Income (Loss), Net of Tax	(1)	2	(3)	21
Accumulated Defined Benefit Plans Adjustment Attributable to Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	0	0	0	0
Accumulated Other Comprehensive Income (Loss) [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance – beginning of period, net of tax	(9,822)	(8,666)	(10,185)	(1,074)
Other Comprehensive Income (Loss), Net of Tax	(1,696)	(3,450)	(1,333)	(11,042)
Balance – end of period, net of tax	$ (11,518)	$ (12,116)	$ (11,518)	$ (12,116)